Heat exchanger



March 15, 1966 P. EDBERG HEAT EXGHANGER Filed July 16, 1963 United States Patent O 3,249,267 HEAT EXCHANGER Per Edherg, Spring Garden Township, York County, Pa., assigner to Borg-Warner Corporation, Chicago, lll., a corporation of Iliinois Filed .iuly 16, 1963, Ser. No. 295,345 2 Claims. (Cl. 165-159) This invention relates to improvements in heat ex changers.

The type of heat exchanger to which the present invention is directed is commonly referred to as a baflied, shell and tube heat exchanger, the term, shell and tube, being generic to a wide variety of designs including U-tube, fin tube, fixed tube sheet, floating head and many others. Consequently, since the invention is more particularly directed to the manner in which the baffles are arranged within the heat exchanger shell, this specification describes a representative fixed tube sheet heat exchanger which includes a series of How-directing cross bales to obtain improved heat transfer performance.

In the manufacture of baflled heat exchangers, it has been established that a loss of heat transfer efficiency is caused by clearance space between and internal surface of the shell and the peripheral edge of the baffles. These clearance spaces provide auxiliary iiow paths which cause short circuiting of fluid and results in a reduction of the effectiveness of the bafiies as flow-directing means and a corresponding loss in heat transfer performance. In other words, a small portion of the shell-side fluid passes along the inside surface of the shell thereby avoiding the effect of the bafiies in directing the fluid into heat exchange contact with the tube bundle or other heat exchange fluid conducting means disposed within the shell.

Clearance space between the baies and the shell, has, for all practical purposes, been unavoidable because of the characteristic variations in the internal diameter and out-of-roundness of the heat exchanger shell, and the manufactured tolerance on the outside diameter of the baies. These variations and tolerances could be eliminated with more precise manufacturing techniques, but the additional expense would outweight the advantages gained by having a close fit between the shell and the baflles. This invention therefore proposes a novel and inexpensive technique for effecting a close, substantially sealing fit between the baffles and the heat exchanger shell.

It is therefore a principal object of the present invention to provide an improved heat exchanger including a shell formed in a manner to support the baffles so that undesirable clearance space is eliminated.

Other and more particular objects and advantages will be apparent from a reading of the following detailed description taken in conjunction with the drawings, wherein:

FIGURE l is a partial top plan View, partly in crosssection, of a heat exchanger constructed in accordance with the principles of the present invention;

FIGURE 2 is a cross-sectional View taken along the plane of line 2 2 of FIGURE 1;

FIGURE 3 is a detailed cross-sectional view taken along the plane of line 3 3 of FIGURE l; and

FIGURE 4 is a plan View of one of the heat exchanger baffles.

Referring now to FIGURE l, there is shown a heat i exchanger comprising an elongated cylindrical shell 10, headers 11 (only one of which is shown), and heat exchange tube means forming a tube bundle 12 disposed within the heat exchanger shell 10. The terminal portions of each of the tubes 1li forming tube bundle 12 are fixedly secured to a pair of tube sheets 16 (only one of which is shown) dividing the shell from the header 11. The tubes are supported between the tube sheets 16 by baflie means 3,240,267 Patented Mar. 15, 1966 comprising a series of baffles 18 which are arranged alternately in spaced relation on opposite sides of the heat exchanger shell 1? to provide a tortuous path for a first heat exchange fluid, herein referred to as the shell-side fluid, from the inlet 2i) at one end of the shell to an outlet (not shown) at the other end of said shell. The baffles are held in fixed relation with respect to one another by a series of spacer rods 22 extending axially of the heat exchanger shell near the inside surface thereof (after assembly). Each spacer rod 22 is provided with spaced notches 23 receiving a corresponding notch 24 in the rnarginal portion of each of the baffles 18 and serving to locate the bafiies in spaced relation. The spacer rods 22 are further provided with an axially extending notch 26 along the edge adjacent to the shell 10 for a purpose which will be apparent from the following description.

A pair of headers 11 (only one of which is shown in FIGURE l) are secured to the tube sheets 16, said headers comprising a shell portion 30 and an end disc 31. Each header 11 is further provided with an outlet (or inlet) 32 for a second heat exchange iiuid, hereinafter referred to as the tube-side fluid. It should be understood that the construction of the header (not shown) at the opposite end of the shell is substantially identical to the header at the left end of the shell as shown in FIGURE 1.

As best illustrated in FIGURE 4, each of the baffles 18 comprises a generally circular piece of metal plate stock having a chordal segment removed from one side to afford a passage for the shell-side fluid. The baie elements are further provided with a plurality of apertures 19 which are adapted to support the heat exchange tubes 14 extending therethrough.

An important aspect of the present invention, as noted in the preliminary remarks, is the provision of improve-d means for substantially eliminating undesirable clearance space between the heat exchanger shell 10 and the peripheral edges 18a of each baie 18. This object is accomplished by assembling the baffles inside the shell and then subjecting the shell to radially inwardly directed forces to deform the shell on both sides of each bafiie. By limiting the deformation of the shell to narrow bands encircling said shell on both sides of each bafiie, an integral radially inwardly extending proiection 28 is formed, said projection being located immediately adjacent to the sides of each bafile near its periphery. When the shell is deformed or restricted in this manner, the area of the shell between projections 28 is also forced into engagement with the peripheral edge 18a to further effect the sealing relationship betwen the baflie and the shell. It will be noted that the notches or recessed portions 26 on the spacer rods serve to accommodate the projections 28,

The deformation of the shell, in a preferred manner of practicing the invention, is carried out by first fabricating the tubes, the baffles and the spacer rods into a subassembly and then inserting the sub-assembly into the shell 10. Thereafter, the entire heat exchanger is mounted on means, such as for example, a lathe or similar device, to rotate the shell about its longitudinal axis. While the heat exchanger is being rotated, a deforming tool, preferably in the form of a hardened steel roller, is forced radially inwardly against the shell in the area adjacent to each of the bailies. This procedure insures that the deformation of the shell is accurately located in the manner indicated above and results in a unit in which the baies are securely fixed into position, with substantially no clearance between the baflies and the shell except in the area provided by the removal of the chordal segment.

While this invention has been described in connection with a certain specific embodiment thereof, it is to be understood that this is by way of illustration and not by way of limitation; and the scope of this invention is dened solely by the appended claims which should be construed as broadly as the prior art will permit.

What is claimed is:

1. A heat exchanger comprising: a shell including a generally cylindrical, rigid wall having predetermined internal dimensions; heat exchange tube means disposed within said shell; means for passing a rst fiuid inside said tube means; means for passing a second fluid into and through said shell in heat exchange relation with the outside of said tube means; a plurality of axially spaced, cross-flow bafes arranged within said shell to provide a tortuous path for said second fluid, said bafes having marginal edges generally conforming to and spaceclfrom said cylindrical wall, the diametral dimensions of said batlies being less than said internal dimensions of said cylindrical Wall, said cylindrical wall being deformed inwardly at axially .spaced locations adjacent to and on opposite sides of the marginal edges of said bailies to provide circumferential, inwardly extending projections integral with said Wall and engaging the marginal edges of said baffles, whereby said projections insure a sealing fit between said shell and said baies to reduce leakage between said balles and said cylindrical wall.

2. A heat exchanger as defined in claim 1 including a plurality of elongated spacer rods having axially spaced notches, and means defining circumferentially spaced, complementary notches on the marginal edges of said balles interengaging said spacer rod notches to locate said baies in spaced relation.

Reerences Cited by the Examiner UNITED STATES PATENTS ROBERT A. OLEARY, Primary Examiner.

KENNETH W. SPRAGUE, CHARLES SUKALO, FREDERICK L. MATTESON, JR., Examiners. 

1. A HEAT EXCHANGER COMPRISING: A SHELL INCLUDING A GENERALLY CYLINDRICAL, RIGID WALL HAVING PREDETERMINED INTERNAL DIMENSIONS; HEAT EXCHANGE TUBE MEANS DISPOSED WITHIN SAID SHELL; MEANS FOR PASSING A FIRST FLUID INSIDE SAID TUBE MEANS; MEANS FOR PASING AS SECOND FLUID INOT SAID THROUGH SAID SHELL IN HEAT EXCHANGE RELATION WITH THE OUTSIDE OF SAID TUBE MEANS; A PLURALITY OF AXIALLY SPACED, CROSS-FLOW BAFFLES ARRANGED WITHIN SAID SHELL TO PROVIDE A TORTUOUS PATH FOR SADI SECOND FLUID, SAID BAFFLES HAVING MARGINAL EDGES GENERALLY CONFORMING TO AND SPACED FROM SAID CYLINDRICAL WALL, THE DIAMETRAL DIMENSIONS OF SAID BAFFLES BEING LESS THAN SAID INTERNAL DIMENSIONS OF SAID CYLINDRICAL WALL, SAID CYLINDRICAL WALL BEING DEFORMED INWARDLY AT AXIALLY SPACED LOCATIONS ADJACENT TO AND ON OPPOSITE SIDES OF THE MARGINAL EDGES OF SAID BAFFLES TO PROVIDE CIRCUMFERENTIAL, INWARDLY EXTENSING PROJECTIONS INTEGRAL WITH SAID WALL AND ENGAGING THE MARGINAL EDGES OF SAID BAFFLES, WHEREBY SAID PROJECTIONS INSURE A SEALING FIT BETWEEN SAID SHELL AND SAID BAFFLES TO REDUCE LEAKAGE BETWEEN SAID BAFFLES AND SAID CYLINDRICAL WALL. 